Closing of wells at points of diameter change



Jan. 25, 1966 H,M.GREENE,JR

CLOSING OF WELLS AT POINTS OF DIAMETER CHANGE Filed June 17, 1963 ii dz 520 is 2 Sheets-Sheet 2 HVVENTUR. fins/(44 M. GREENE, JP,

ATTOQNEY United States Patent 3,231,020 CLQSING OF WELLS AT POINTS OF DIAMETER CHANGE Haskell M. Greene, Jr., 671 Galen, La Habra, Calif. Fiied .Iune 17, 1963, Ser. No. 288,301 11 Claims. (Cl. 166-63) This invention relates to improved methods and apparatus for forming a closure in a well bore at a location at which the diameter of the well bore decreases. Certain features of the invention have been disclosed and claimed broadly in my copending application Serial Number 288,260, entitled, Formation of Closures in Well Bores, and filed of even date herewith.

The production liner of a well is usually of a smaller diameter than is the casing just above the liner, and consequently there is in most instances an abrupt change in diameter of the well bore at the upper end of the liner. Similarly, there may be other points in the well where the size of the casing changes from a relatively large size above a particular point to a substantially reduced diameter beneath that point. The present invention is particularly concerned with instances in which there is such a change in diameter, either at the liner location or at some other point in a well, and in which it subsequently becomes desirable to close off the well at the point at which the diameter changes. For instance, it may be desired to close the well at the mentioned location so that the well may be worked on in some way above that point, following which it may be desirable to again open the well to its initial condition.

A major object of the invention is to provide methods and apparatus for thus closing a well at a change of diameter location, and in a manner positively preventing any fiuid flow between the upper portion of the well and either the reduced diameter pipe beneath that point, or the space about that pipe. Further the invention will serve to form this seal even though the smaller diameter pipe in the lower portion of the well is not exactly concentric with respect to the upper casing, with the result that the mentioned space about the upper end of the lower pipe is not of true annular configuration and therefore could not be sealed by many conventional methods.

To attain the discussed results, I utilize a novel tool which is lowered to the zone to be sealed, and which carries a plug or bridging element or assembly adapted to seat against a shoulder and thereby form a bridge at least partially closing off the lower reduced diameter zone. In conjunction with this plug, or bridging element, the tool carries a mass of discrete bodies in solid form, such as gravel and/or sand, with these bodies being supported by the plug in a position to extend across the transverse dimension of the upper enlarged diameter portion of the well. Above the mass of discrete solid bodies, I may position a quantity of at least partially liquid material, preferably a cementitious material, and for best results a Portland cement mix. The tool deposits this cement or other substance above the gravel and/or sand, so that the cement may cure, and form with the other elements a completely effective closure in the well. The sand and/or gravel serves to prevent any of the cemcntitious material from passing downwardly therethrough to a lower point in the well. If it later becomes desirable to reopen the well, as very frequently occurs, the cement, sand and/or gravel, and the bottom plug may be easily drilled out.

Certain specific features of the invention reside in a preferred construction for the plug, which will greatly facilitate subsequent drilling of the plug for reopening the well. In this connection, I find it desirable to employ a plug which includes a preferably rigid block of cast and cured non-metallic material, such as cement, brick, or the like, Portland cement being the preferred substance for this purpose. In conjunction with this block, there may in some instances be provided a sealing element, at the underside of the block, to seat on the shoulder in the well and form a seal therewith. The plug or bridging structure may initially be supported by the tool by means of a connector which extends downwardly through the mass of discrete solid bodies, and which is protected against contact with those bodies by reception within a shielding tube. The connector may be a chain, which may be released upon rupture of a cement retaining frangible disc, upon firing of the tool. Also, the chain may be designed to automatically break at a predetermined point upon firing, to allow one portion of the chain to remain attached to the plug upon release of the plug, while another portion remains attached to a different portion of the apparatus.

The above and other features and objects of the invention will be better understood from the following detailed description of the typical embodiment illustrated in the accompanying drawings in which:

FIG. 1 is a view representing a tool embodying the invention as it appears when positioned at a well zone which is to be closed;

FIG. 2 is an enlarged fragmentary vertical section through a portion of the tool of FIG. 1;

FIG. 3 is an enlarged fragmentary vertical section through a second and lower portion of the FIG. 1 tool;

FIG. 4 i a transverse section taken on line 4-4 of FIG. 2;

FIG. 5 is a view similar to FIG. 1, but showing the closure after the tool has been actuated;

FIGS. 6 and 7 are perspective and side views of one of the chains used in the apparatus; and

FIG. 8 is a view showing the ultimate closure in a second well situation.

With reference to FIG. 1, I have shown at 10 the casing of a well, at a location spaced beneath the surface of the earth. The casing may terminate downwardly at 11, and carries at its lower end a conventional production liner 12 containing apertures 13 through which the production fluid enters the liner for delivery upwardly to the surface of the earth. The upper end of the liner is suspended within or connected to the lower end of casing 10 by a liner hanger or seal ring represented at 14, and received radially between casing 111 and liner 12. The upper end of the liner, and/ or the upper surface of ring 14, thus form a shoulder or shoulders 15 facing upwardly against which a seal member may seat.

The number 16 in FIG. 1 represents generally a tool which is to be utilized. for forming a closure or seal at the lower end of casing 10. Tool 16 has a tubular vertically extending body 17 which is closed at its upper end by a cover or top wall structure 18 connected to a wire line 19 by which the tool is suspended within the well, and is adapted to be lowered into and removed upwardly from the well. Line 19 is actuated by suitable conventional equipment at the surface of the earth. The side wall of body 17 is formed of a series of vertically successive threadedly interconnected pipe sections or stands, two of which are designated 17a and 17b in FIG. 1. These two sections are joined together by a threaded connection at 20, and act to support at that connection a frangible disc 21 which retains above the disc a mass of unset Portland cement mix 22 to ultimately be deposited in the well. Above the level of the cement mix, body 17 contains a gas producing charge 23, which may be suspended from top wall 18 of the body, and which is capable of producing large quantities of gases very suddenly upon actuation. Charge 23, may desirably be formed of a suitable combustible propellent charge, such as any rifle powder (for Patented Jan. 25, 1966- 3 example E. I. du Pont de Nemours Powder No. 4320 or 4350). It is to be understood, however, that, if desired, charge 23 may be a container of high pressure carbon dioxide, or other liquid, gaseous or solid material adapted upon opening of the container to emit in the form of large volumesof gases.

The lower end of the side wall of main tool body 17 terminates in a bottom circular edge 24, so that the contents of the body may ultimately discharge downwardly from the tool. Just beneath bottom edge 24, the tool carries a plug or bridging assembly 25 which is adapted to close the upper end of liner 12. Plug 25 includes a bottom seal element 27 which may be formed of a suitable resilient elastomeric material such as rubber, and which is engageable with one or both of the shoulders at the upper end of the liner to form an annular seal therewith. Preferably, the undersurface 26 of element 27 tapers downwardly, as shown, to maximize the effectiveness of the seal. Projecting downwardly from element 27, and rigidly secured thereto, plug has a rigid rod 28, carrying resilient locking fingers 29, which normally expand outwardly to the FIG. 1 condition, but which are contractible radially inwardly upon engagement with liner 12,- to enter and move downwardly within the liner. Fingers 29 are directed angularly upwardly, and have sharp outer ends, acting to bite into the material of liner 12 and prevent upward movement of plug 25 relative to the liner after the plug has been moved downwardly to the FIG. 5 sealing position.

Connected to the upper side of seal element 27, plug 25 includes a relatively heavy body of reinforcing material 30. This body may be externally of cylindrical configuration, centered about the main vertical axis 31 of the well, and may have an external diameter which is somewhat smaller than that of the largest portion 32 of seal element 27. The upper surface 33 of block 30, and its lower surface 34, may both be disposed horizontally, and perpendicular to axis 31 of the well and tool, with surface 34 resting on a correspondingly transverse and horizontal surface 35 of element 27. Parts Z7, 23 and may be rigidly secured together in some manner, as by extension 1218 of rod 28 upwardly through element 27 and to a position of embedded retention within block 30.

Block 30 is formed of a rigid block of cast and cured drillable non-metallic material, as mentioned previously, preferably cured Portland cement, and therefore may be impervious to the liquids encountered in the well, and adapted to maintain its integrity during lowering and after positioning in its FIG. 5 ultimate setting.

Contained within body section 17b, above cement block 30,- the tool carries a mass 36 formed of a large number of discrete bodies of solid material. This mass 36 may consist of gravel and/ or sand. In instances in which the element 143 closes the space about the upper end of liner 12 rather completely, mass 36 may be a fairly fine sand along the entire vertical extent of the mass. If, however, element 14 does not form a very efiective closure, or for some reason is completely absent, then some or all of the mass 36 should be formed of rocks or gravel large enough in size to avoid their falling downwardly through the space about the liner. FIGS. 1 and 3 illustrate a situation in which several layers of different size discrete bodies are employed, the bottom layer 37 consisting of relatively large rocks or gravel, a mixed upper layer 38 of somewhat smaller gravel, a third layer 39 of coarse sand, and an upper layer 49 of very fine sand. The gravel 37 or 38 may be formed of limestone or other rock having rather sharp edges, capable of biting into the side wall of casing 10 and thereby resisting displacement from a predetermined desired position within that casing.

Plug 25 is supported in its FIG. 1 position, against the bottom edge 24 of the tool body, by means of two pref-- erably flexible connector elements 41 and 42, typically taking the form of chains of the type shown in FIGS. 6

and 7. The upper end of chain 41 may be connected at 43 to the underside of frangible disc 21, while the lower end of chain 41 is connected through an adjusting element 44 to a lever 45 pivoted at 46 to a bracket connected to the side wall 17 of the tool body. Element 44 may extend through an aperture 47 in lever 45, and be threadedly connected to a nut 48, which is adjustable to vary the position in which the lever is held by chain 41. A similar element 49 and adjusting screw 50 adjusts the position in which chain 42 is suspended by the lever. It is noted that the position of connection of chain 42 to lever 45 is much closer to the fulcrum point 46 than is the position of connection of chain 41 to the lever, the lever arm associated with chain 41 preferably being several times as great as the lever arm associated with chain 42, so that the force exerted downwardly on disc 21 by chain 41 is not as great as the force exerted downwardly by chain 42 on lever 45. The preferred ratio between these two lever arms is considered to be at least about six to one.

Chain 42 extends downwardly through a tube 51, typically formed of a suitable rigid metal, and is con-- nected at its lower end to cement block 30, as by means of a connector eye 52 (FIG. 3) secured to the upper surface of the block. The lower end of tube 51 restson the upper surface 33 of block 30, while the upper end of the tube projects upwardly beyond the top of' mass 36, with mass 36 being received entirely at the outside of the tube, so that the tube prevents contact of the chain with any of the gravel or the sand. As a result, the gravel and sand can not interfere with the downward movement of the chain upon firing of the device. In or-der that tube 51 may be retrieved with the tool after firing, the tube may be connected to side wall 17b, as by means of a ring 151 (FIG. 2) disposed about tube 51 and engageable in supporting relation with a flange 152 on the tube. Ring 151 may be rigidly connected to wall 17b by an arm 153 or a suitable spider type mounting.

Disc 21 may be formed of any material capable of being ruptured upon firing of gas producing charge 23. As examples, disc 21 may be formed of a suitable aluminum alloy, or an appropriate resinous plastic material. The disc is retained in position by confinement of its peripheral flange 53 between a shoulder 54 formed on body section 17b and the end of body section 17a. Access is provided to lever 4'5 and the connected chain through an access opening 55, so that the chains may be adjusted upon initial assembly of the tool.

Chain 42 is designed to automatically part or be broken at a location 55, in response to downward movement of the chain. For this purpose, two of the links 42a and 42b of chain 42 may be initially held together only by extension therethrough of the end of a wire 57, whose other end is secured at 58 to the body wall 17. More specifically, the chain may typically be of the known type illustrated in FIGS. 6 and 7, with each link being formed of a piece of sheet metal, appropriately apertured and doubled back in the illustrated form. The loop formed at the lower end of each link passes through the openings in the next successive link, except at the lo cation of links 42a and 4%, at which location links 42a and 42b are disconnected except for the extension therethrough of the previously mentioned wire 57. It will of course be obvious that, if links 42a and 4211 move downwardly through a short distance, they will move away from engagement with wire 57, and consequently the chain will break at the location 56.

In preparing the tool 16 for use, the charge 23 and cement mass 22 may first be located within the upper portion of the tool, with the cement being retained by disc 21. Next, plug 25 may be moved into position, and chains 41 and 42 assembled and adjusted to properly hold the plug against the lower edge 24 of the tool body. Finally, the gravel and/ or sand 36 may be filled into the lower body section 1712, about tube 51, and in a position of support by plug 25. With the apparatus in this condition, wire line 19 is actuated to lower the tool into the well, and to the FIG. 1 position just above the upper end of liner 12. While the tool is in this position, charge 23 may be actuated to suddenly release a large quantity of gases within the upper end of the tool body. These gases exert a sudden downward force against the partially liquid cement mix 22, which force acts through the cement to rupture disc 21 and thereby release the support of plug 25 through chains 41 and 42. The plug then falls downwardly under the influence of gravity, with the resultant downward movement of chain 42 causing that chain to break at 56 so that lever 45 and its connected parts need not move downwardly with the plug. The weight of the plug is suflicient to cause it to fall downwardly to the FIG. 5 position, in which seal element 27 annularly engages shoulders in a relation closing off liner 12. At the same time, the gravel and sand 36 fall downwardly above the plug, to the position illustrated in FIG. 5, and as the tool 17 is subsequently withdrawn upwardly to the surface of the earth, the cement falls out of the lower end of the tool and onto the gravel and/ or sand to form a composite plug assembly consisting of the bottom seal plug 25, the intermediate sand and gravel thereabove, and a mass of cement at the top. The cement ultimately sets or cures to a hardened conditions, to form a completely positive and eifective seal in the hole. If it is later desired to reopen communication between casing 10 and liner 112, this may be done by merely drilling downwardly through the cement, sand, gravel, cement block 30, and seal element 27. All of these elements are much easier to drill than is the metal body of a conventional bridge plug which has been necessary in the past for attaining the function of the present apparatus and methods.

FIG. 8 represents a situation in which the present apparatus and method have been used to form a closure between a lower reduced diameter casing or tube 12' and an upper casing 10' where the annular space between these parts is not closed by an element corresponding to that shown at 14 in FIG. 1. In this case the gravel 37 (corresponding to gravel 37 in FIG. 3) is large enough to assure against its falling downwardly through the space radially between elements 10 and 12', and therefore acts to support the sand and cement thereabove in spite of the absence of element 14 of the first form of the invention. It is also noted that the closure arrangement of FIG. 8 is eflective regardless of whether or not the two pipes 10' and 12' are concentric, since the gravel, sand and cement seal may be formed even though pipe 12' may be offset considerably with respect to the center of pipe 10' (such an oflset arrangement being typically illustrated in FIG. 8).

Another variational form of the invention, which will be easily understandable without further illustration, utilizes apparatus identical with that of FIG. 1, except that the seal element 27 of plug is omitted from the device. The cement block 30 then functions by itself as the entire bridging element or plug, with block 30 seating downwardly against element 14, or against the upper end of liner 12 if element 14 is not present (as in FIG. 8). Though block 30 may not seal the upper end of liner 13 completely, the block does close the well sufficiently to prevent gravel 37 from falling downwardly past the block, so that the block effectively supports the gravel and sand, and ultimately the body of cement 22, to form therewith a completely positive and effective closure in the well.

As has been discussed in greater detail in my above identified co-pending application Serial No. 288,260, the presence of the gravel and sand above plug 25 of FIG. 1 reduces the amount of downward well fluid pressure which may be exerted on the plug, so that the plug does not have to be constructed strongly enough to withstand the' entire downward fluid pressure in the well. This is true partially because downward pressure exerted against the upper surface of sand layer 40, after the sand and gravel have been discharged from the tool into the well, tends to force the sand and gravel, particularly the latter, radially outwardly against the well casing, to bite into that casing and resist downward movement of the overall mass of discrete particles. Also, the reduction in downward fluid pressure at the location of plug 25 is further enhanced by the progressive reduction in size of the dis crete particles in an upward direction, from lower course gravel layer 37 to upper fine sand layer 40. More particularly, since upper layer 40 contains a smaller void space or volume for a given vertical thickness of the sand mass than does the course gravel of layer 37, fluid flowing downwardly under pressure through the different layers will have a greater pressure in layer 40 than in layer 37. This is true because the product of fluid pressure times the eflective volume of the fluid passage through layer 40 must equal the corresponding product of pressure times volume in layer 37. If for example the void space or volume in layer 37 is 200 times as great as the corresponding void space or volume in layer 40, then the pressure in layer 37 will be only as great as the pressure within layer 40. To attain this advantage, it may in some cases be desirable to purposely omit seal element 20, as discussed above, in order to assure the maintenance of some downward flow of fluid prior to the time that the cementitious material 22 falls downwardly into contact with upper sand layer 49. When this cementitious material does engage the sand, in the ultimate condition illustrated in FIG. 5, the cement completely closes the passages in the upper surface of sand layer 40, to prevent further downward flow of any well fluid. Also, the fine passages between the different particles of sand in layer 40, though large enough to initially pass well fluid downwardly therethrough, are sufficiently small to prevent the cementitious material 22 from flowing downwardly through the sand, so that the cement is effectively supported on the upper surface of the sand and may harden in that condition.

I claim:

1. Apparatus for forming a closure in a well bore at the location of an upwardly facing shoulder therein at which the diameter of the well decreases from an upper larger diameter portion to a lower reduced diameter portion, said apparatus including a tool body structure to be lowered into the well to a predetermined zone therein, a bridging element carried by said body structure and releasable therefrom and adapted to seat downwardly against said shoulder and extend at least partially across said lower reduced diameter portion of the well, a mass of discrete bodies of material in solid form carried by said tool body structure and adapted to be released in the well above said bridging element and be supported thereby, a mass of uncured cementitious material carried by the tool body structure and adapted to be deposited in the well above said mass of discrete bodies, a support element above said discrete bodies supporting said cementitiou's material, a connector extending upwardly from said bridging element past said mass of discrete solid bodies and connected to said support element, and means preventing said bodies from contacting said connector, said support element being openable to free said cementitious material from said body structure, and said connector being constructed to release said bridging element from said body structure in response to said opening of said support element.

2. Apparatus for forming a closure in a well bore at the location of an upwardly facing shoulder therein at which the diameter of the well decreases from an upper larger diameter portion to a lower reduced diameter portion, said apparatus including a tool body structure to be lowered into the well to a predetermined zone therein, a bridging element carried by said body structure and releasable therefrom and adapted to seat downwardly against said shoulder and extend at least partially across said lower reduced diameter portion of the Well, a mass of discrete bodies of material in solid form carried by said tool body structure above said bridging element and adapted to be released in the well above said bridging element and be supported thereby, a mass of uncured cementitious material carried by the tool body structure above said discrete bodies and adapted to be deposited in the well above said mass of discrete bodies, a frangible member in the tool body structure above said discrete bodies and supporting said cementitious material, and a connector structure attaching said bridging element to said frangible member and extend ing through said mass of discrete bodies, said connector structure being constructed to release said bridging element from said body structure in response to breakage of said frangible member.

3. Apparatus for forming a closure in a well bore at the location of an upwardly facing shoulder therein at which the diameter of the well decreases, said apparatus including a tool body structure to be lowered into the well to a predetermined zone therein, a bridging element carried by said body structure and releasable therefrom and adapted to seat downwardly against said shoulder and including a block of cured cement, carried above said closure element and adapted to be left in the well therewith, a mass of discrete bodies of material in solid form carried by said tool body structure and adapted to be released in the well above said bridging element and said block of cement, a mass of uncured cementitious material carried by the tool body structure and adapted to be deposited in the well above said mass of discrete bodies, a frangible disc above said discrete bodies supporting the cementitious material in said body structure, a lever in the body structure above said discrete bodies and beneath said disc and mounted to swing about a fulcrum location, a first flexible connector exending downwardly from said disc and connected to said lever at a first point spaced from said fulcrum location, a second flexible connector connected to said lever at a point spaced a shorter distance than said first point from said fulcrum location and extending downwardly through said mass of discrete solid bodies and connected to said bridging element, a tube disposed about said second connector and isolating it from contact with said solid bodies, and a propellant charge above said cementitious material for exerting force thereagainst and breaking said disc, said second flexible connector being constructed to break in response to downward movement thereof relative to said body structure upon breakage of said frangible disc.

4. Apparatus for forming a closure in a well bore at the location of an upwardly facing shoulder therein at which the diameter of the well decreases from an upper larger diameter portion to a lower reduced diameter portion, said apparatus including a tool body structure to be lowered into the well to a predetermined zone therein, a bridging element carried by a lower portion of said body structure and releasable therefrom and constructed and positioned to seat downwardly against said shoulder and extend at least partially across said lower reduced diameter portion of the well, a mass of discrete bodies of material in solid form carried by said tool body structure above said bridging element at a location to fall downwardly therefrom into the well and be supported by the bridging element, a mass of uncured cementitious material carried by the tool body structure above said discrete bodies at a location to be deposited in the well above said mass of discrete bodies, a gas producing charge carried by the body structure at the top of said ceinentitious material at a location to apply gas force downwardly thereagainst, a support element in the body structure above said discrete bodies and beneath said cementitious material and supporting said cementitious material in the body structure and constructed to be opened by said gas force transmitted downwardly through said cementitious material, and a connector structure attaching said bridging element to said support element and extending upwardly past said mass of discrete bodies, said connector structure being constructed to release said bridging element from said body. structure in response to said opening of said support element.

5. Apparatus for forming a closure in a well bore at the location of an upwardly facing shoulder therein at which the diameter of the well decreases from an upper larger diameter portion to a lower reduced diameter portion, said apparatus including a tool body structure to be lowered into the well to a predetermined zone therein, a bridging element carried by a lower portion of said body structure and releasable therefrom and constructed and positioned to seat downwardly against said shoulder and extend at least partially across said lower reduced diameter portion of the well, a mass of discrete bodies of material in solid form carried by said tool body structure above said bridging element at a location to fall downwardly therefrom into the well and be supported by the bridging element, a mass of uncured cementitious material carried by the tool body structure above said discrete bodies at a location to be deposited in the well above said mass of discrete bodies, a gas producing charge carried by the body structure at the top of said cementitious material at a location to apply gas force downwardly thereagainst, a support element in the body structure above said discrete bodies and beneath said cementitious material and supporting said cementitious material in the body structure and constructed to be opened by said gas force transmitted downwardly through said cementitious material, a connector structure attaching said bridging element to said support element and extending upwardly past said mass of discrete bodies, and means preventing said bodies from contacting said connector structure, said connector struc ture being constructed to release said bridging element from said body structure in response to said opening of said support element.

6. Apparatus as recited in claim 5, in which said last mentioned means include a tube extending upwardly through said mass of discrete bodies and disposed about said connector structure and isolating it from contact with said bodies.

7. Apparatus for forming a closure in a well bore at the location of an upwardly facing shoulder therein at which the diameter of the well decreases from an upper larger diameter portion to a lower reduced diameter portion, said apparatus including a tool body structure to be lowered into the well to a predetermined zone therein, a bridging element carried by a lower portion of said body structure and relatively movable downwardly therefrom and constructed and positioned to seat downwardly against said shoulder and extend at least partially across said lower reduced diameter portion of the well, a mass of discrete bodies of material in solid form carried by said tool body structure above said bridging element at a location to fall downwardly therefrom into the well and be supported by the bridging element, a mass of uncuredcernentitious material carried by the tool body structure above said discrete bodies at a location to be deposited in the well above said mass of discrete bodies, a gas producing charge carried by the body structure at the top of said cementitious material at a location to apply gas force downwardly thereagainst, a support element in the body structure above said discrete bodies and beneath said cementitious material and supporting said cementitious material in the body structure and constructed to be opened by said gas force transmitted downwardly through said cementitious material, and a connector structure attaching said bridging element to said support element and extending upwardly past said mass of discrete bodies, and preformed to break upon downward movement of the bridging element, said connector structure being constructed to release said bridging element from said body structure in response to said opening of sai-d support element.

8. Apparatus for forming a closure in a well bore at the location of an upwardly facing shoulder therein at which the diameter of the well decreases from an upper larger diameter portion to a lower reduced diameter portion, said apparatus including a tool body structure to be lowered into the well to a predetermined zone therein, a bridging element carried by a lower portion of said body structure and releasable therefrom and constructed and positioned to seat downwardly against said shoulder and extend at least partially across said lower reduced diameter portion of the well, a mass of discrete bodies of material in solid form carried by said tool body structure above said bridging element at a location to fall downwardly therefrom into the well and be supported by the bridging element, a mass of uncured cementitious material carried by the tool body structure above said discrete bodies at a location. to be deposited in the Well above said mass of discrete bodies, a gas producing charge carried by the body structure at the top of said cementitious material at a location to apply gas force downwardly thereagainst, a support element in the body structure above said discrete bodies and beneath said cementitious material and supporting said cementitious material in the body structure and constructed to be opened by said gas force transmitted downwardly through said cementitious material, a connector structure attaching said bridging element to said support element and extending upwardly past said mass of discrete bodies, said connector structure including a lever mounted for swinging movement about a fulcrum, a first elongated connecting element attaching a first portion of said lever to said support element, and a second elongated connecting element attaching to said bridging element a second portion of said lever, which is closer to said fulcrum than is said first portion, said connector structure being constructed to release said bridging element from said body structure in response to said opening of said support element.

9. Apparatus for forming a closure in a well bore at the location of an upwardly facing shoulder therein at which the diameter of the well decreases from an upper larger diameter portion to a lower reduced diameter portion, said apparatus including a tool body structure to be lowered into the well to a predetermined zone therein, a bridging element carried by a lower portion of said body structure and releasable therefrom and constructed and positioned to seat downwardly against said shoulder and extend at least partially across said lower reduced diameter portion of the well, a mass of discrete bodies of material in solid form carried by said tool body structure above said bridging element at a location to fall downwardly therefrom into the well and be supported by the bridging element, a mass of uncured cementitious material carried by the tool body structure above said discrete bodies at a location to be deposited in the well above said mass of discrete bodies, a gas producing charge carried by the body structure at the top of said cementitious material at a location to apply gas force downwardly thereagainst, a support element in the body structure above said discrete bodies and beneath said cementitious material and supporting said cementitious material in the body structure and constructed to be opened by said gas force transmitted downwardly through said cementitious material, a connector structure attaching said bridging element to said support element and extending upwardly past said mass of discrete bodies, said connector structure including a lever mounted for swinging movement about a fulcrum, a first elongated connecting element attaching a first portion of said lever to said support element, and a second elongated connect-ing element attaching to said bridging element a second portion of said lever, which is closer to said fulcrum than is said first portion, said connector structure being constructed to release said bridging element from said body structure in response to said opening of said support element, said second connecting element having a portion preformed to break in response to downward movement thereof relative to said body structure.

10. Apparatus for forming a closure in a well bore, comprising a tool body structure to be lowered into the well to a predetermined zone therein, a bridging element carried by said body structure and releasable therefrom and adapted to extend at least partially across the well, a mass of discrete bodies of material in solid form carried by said tool body structure and adapted to be released in the well above said bridging element and be supported thereby, a mass of uncured cementitious material carried by the tool body structure and adapted to be deposited in the Well above said mass of discrete bodies, a closure at the lower end of said cementitious material retaining it against discharge from the body structure, and a connector structure connecting said closure to said bridging element and extending upwardly past said discrete bodies and releasably holding said bridging element, said connector structure including a lever mounted to swing about a fulcrum location, a first connector extending upwardly from said bridging element and connected to said lever at a first point spaced from said fulcrum location, and a second connector connected to said lever at a point spaced farther than said first point from said fulcrum location and extending upwardly to and connected to said closure.

References Cited by the Examiner UNITED STATES PATENTS 1,641,741 9/1927 Davis et al 166-135 1,687,424 10/1928 Boynton 166-195 X 1,925,017 8/1933 Wells 166-195 X 2,086,409 7/1937 Emery 166-117 2,125,231 7/1938 Hurst 166-195 X 2,263,566 11/1941 Boynton 166-193 X 2,710,065 6/1955 Hamilton 166-192 2,969,839 1/1961 Greene.

3,064,734 11/1962 Toelke 166-63 3,079,997 3/1963 Blydorp 166-117 X OTHER REFERENCES Scott, R. W.: How Through-Tubing Bridge Plugs Work; in World Oil, 149 (5) October 1959, pp. 141-149.

CHARLES E. OCONNELL, Primary Examiner. BENJAMIN HERSH, Examiner. 

1. APPARATUS FOR FORMING A CLOSURE IN A WELL BORE AT THE LOCATION OF AN UPWARDLY FACING SHOULDER THEREIN AT WHICH THE DIAMETER OF THE WELL DECREASES FROM AN UPPER LARGER DIAMETER PORTION TO A LOWER REDUCED DIAMETER PORTION, SAID APPARATUS INCLUDING A TOOL BODY STRUCTURE TO BE LOWERED INTO THE WELL TO A PREDETERMINED ZONE THEREIN, A BRIDGING ELEMENT CARRIED BY SAID BODY STRUCTURE AND RELEASABLE THEREFROM AND ADAPTED TO SEAT DOWNWARDLY AGAINST SAID SHOULDER AND EXTEND AT LEAST PARTIALLY ACROSS SAID LOWER REDUCED DIAMETER PORTION OF THE WELL, A MASS OF DISCRETE BODIES OF MATERIAL IN SOLID FORM CARRIED BY SAID TOOL BODY STRUCTURE AND ADAPTED TO BE RELEASED IN THE WELL ABOVE SAID BRIDGING ELEMENT AND BE SUPPORTED THEREBY, A MASS OF UNCURED CEMENTITIOUS MATERIAL CARREID BY THE TOOL BODY STRUCTURE AND ADAPTED TO BE DEPOSITED IN THE WELL ABOVE SAID MASS OF DISCRETE BODIES, A SUPPORT ELEMENT ABOVE SAID DISCRETE BODIES SUPPORTING SAID CEMENTITIOUS MATERIAL, A CONNECTOR EXTENDING UPWARDLY FROM SAID BRIDGING ELEMENT PAST SAID MASS OF DISCRETE SOLID BODIES AND CONNECTED TO SAID SUPPORT ELEMENT, AND MEANS PREVENTING SAID BODIES FROM CONTACTING SAID CONNECTOR, SAID SUPPORT ELEMENT BEING OPENABLE TO FREE SAID CEMENTITIOUS MATERIAL FROM SAID BODY STRUCTURE, AND SAID CONNECTOR BEING CONSTRUCTED TO RELEASE SAID BRIDGING ELEMENT FROM SAID BODY STRUCTURE IN RESPONSE TO SAID OPENING OF SAID SUPPORT ELEMENT. 